The supplied Straight Union Pneumatic Fitting connects two tubes of the same diameter for an inline air connection. The fitting allows for easy connection and disconnection from other pneumatic components through male and female connectors and receptors. Pneumatic fittings are parts used to connect sections of pipe, tube, and hose in pneumatic (pressurized gas) systems. Compared to hydraulic fittings, pneumatic fittings are typically characterized by tighter seals and lower pressure requirements. The Straight Union Pneumatic Fitting is very efficient and useful.